Subject: Re: 68k assembly question
To: Kevin Radke <radke@cpre1.ee.iastate.edu>
From: Hauke Fath <saw@sun0.urz.uni-heidelberg.de>
List: port-mac68k
Date: 07/13/1996 03:56:56
At 15:26 Uhr 12.07.1996, Kevin Radke wrote:
>Are there any motorola 68k assembly language
>wizards out there?
>
>I would like to know what is the *fastest* I could
>access a memory location.
>
>I.E. I have a device that does something when you
>read from a certain memory location.  I don't really
>care what is at this location, I just need to acces it.
>I would also rather not kill off any registers if
>possible. (Or else moveb would probably be best...)


Hi,

I would give

        lea     yourAddress, a0
        ...
        tst.b (a0)

a try. It checks a memory location and sets the flags accordingly, but
doesn't change any register contents. 12 clock cycles on a 68000 (I haven't
got any newer manuals).

What are you trying to do, anyway? 'just need to access' rings some bells
for me...



	hauke

---
"It's never straight up and down"     (DEVO)